Cell division Flashcards
where does DNA exist?
in the nucleus as thin strands
what happens when the cells containing nuclei are ready to divide?
the DNA copies itself then coils and condenses to form chromosomes.
what is each chromosome made up of?
what does each section of a single molecule of dna have?
a single molecule of DNA
-it contains a code for the production of a particular protein called a gene.
what does each human body cell contain?
how could they be arranged?
what does each chromosome in this pair carry?
-46 chromosomes.
-into 23 pairs.
-the same types of genes.
what is the 23rd pair?
difference between the female and male chromosomes + features?
-the sex chromosome
-females = XX (2 chromosomes that are identical in shape)
-males = XY (one of the chromosomes is different)
cells divide when: (3)
-an organism grows
-an organism becomes damaged and needs to produce new cells for repair
-organisms like bacteria reproduce asexually
what is essential for the new cells produced to contain?
genetic information that is identical to the parent cell.
describe the stages of a cell cycle: (5)
- cell cycle involve cell growth, synthesis of DNA.
- chromosome produces an exact copy of itself.
-after this a period of further growth occurs and the DNA is checked for errors.
-mitosis occurs after this checking has been completed.
-finally the cytoplasm of the cell separates and two cells are formed.
what happens during mitosis?
what is produced?
-diploid cell undergoes a type of cell division
-two genetically identical diploid daughter cells
the length of different stages of the cell cycle can be estimated using the formula:
length of time in phase = (observed number of cells at that stage/ total number of cells observed) x total length of time of cell cycle
what are the daughter cells? and why?
clones of each other
-as every base pair of their DNA is identical.
interphase: (2)
-the cell spends most of its life in this phase.
-the DNA in chromosomes copies itself ready for mitosis
prophase: (2)
-the DNA in chromosomes and their copies condenses to become more visible.
-the membrane around the nucleus disappears.
metaphase:
Chromosomes and their copies line up in the middle of the cell.
anaphase:
Chromosomes and their copies are pulled to different ends of the cell.
telophase:
New membranes form around the chromosomes at each end of the cell.
cytokenesis:
The cell membrane pinches in and eventually divides into two daughter cells.
what happens when a cell becomes cancerous? (2)
-it begins to grow and divide uncontrollably.
-new cells are produced even if the body does not need them
what does a group of cancerous cells produce?
a growth called a tumour.
what are the two types of tumours?
benign and malignant
characteristics of a benign tumour: (3)
-grow slowly.
-usually grow within a membrane, so can easily be removed
-do not invade other parts of the body.
characteristics of a malignant tumour? (3)
-grow quickly.
-invades neighbouring tissues and can spread to other parts of the body in the bloodstream.
-as the tumour grows, cancer cells detach and can form secondary tumours in other parts of the body.
what is the process of cancer cells detaching and forming secondary tumours in other parts of the body called?
metastasis
what are cancer cells? (in terms of functionality)
-what does this mean?
undifferentiated – they do not carry out their normal function.
how do genetics play a part in cancer?
genetic factors that increase the likelihood of developing some cancers
what are carcinogens?
Chemicals and other agents that can cause cancer
what do carcinogens do? and how? (2)
-cause cancer by damaging DNA.
-as they cause mutations to occur
why are we more likely to develop cancer as we get older? (3)
-a single mutation will not cause cancer.
-several are required for this to occur.
-hence we are more likely to develop cancer as we get older.
